This invention relates to the play of software (e.g., motion picture) carriers, and more particularly to a data block format for such carriers and players therefor that allows efficient use of the bit capacity of the carrier so that numerous signals may be represented on the same carrier.
In accordance with the principles of the invention, all signals are represented by respective bit streams. Successive data blocks may contain a sufficient number of video bits to represent multiple frames, but not necessarily a number of frames or a number of bits which is the same for each block. In fact, it is not necessary that a block contain any data which represents image frame information. Similarly, a block may contain data which represents one or more soundtracks, with the bits not necessarily representing the same time duration for each soundtrack; it is also possible that a particular soundtrack will not be represented at all in a particular block, while other soundtracks may be. If subtitle information is provided, it too is represented in the data blocks. If subtitles are provided in multiple languages from which the user selects one, it is possible for the different-language subtitles corresponding to the same scene being contained in totally different data blocks. The basic operating principle is that the bit rate (represented by the number of bits read from the disk per unit time) for each signal is a function of that signal rather than a function of a bit rate requirement for the disk as a whole. Because the number of bits for an individual signal that are stored in a particular data block may range from none to many (where xe2x80x9cmanyxe2x80x9d means many relative to the number of bits stored for other signals), each data block identifies the kinds of bit information stored in it, and the bits representing one signal are delineated from bits representing another. But as long as it is made clear what each group of bits in a data block represents, each signal can enjoy its own data rate to thereby maximize efficient use of the overall bit capacity of the disk.
This is not to say that a large group of data blocks should be used to store video information, a succeeding large group should be used to store audio information, etc. Such a scheme is possible with sufficiently long buffers, but the buffers would be needlessly long. There is a different buffer provided in the player for each signal to be generated from the disk, with the bits representing each signal being loaded into a respective buffer as they are read, and with each signal being generated by reading bit information from the respective buffer at the proper rate. Because the several signals are usually synchronized with each other, the several bit streams must be processed in a synchronized manner. This means that there must always be bits available in the buffers for all signals as they are required. This, in turn, means that while each buffer need not be kept full, it must always contain enough bits for immediate needs. At the other extreme, the reading of data blocks must stop when any buffer is full because any bits fed to that buffer will be lost (or they will replace other bits in the buffer which will be lost). Consequently, the required hardware control is that reading of data blocks temporarily cease when any buffer is full, with the bits representing different signals being distributed among the data blocks such that every buffer at all times has a sufficient number of bits for immediate needs.
The invention is disclosed in the context of an overall system which offers numerous advantageous features. The entire system is described although the appended claims are directed to specific features. The overall list of features which are of particular interest in the description below include:
Video standard and territorial lock out.
Play in multiple aspect ratios.
Play of multiple versions, e.g., PG-rated and R-rated, of the same motion picture from the same disk, with selective automatic parental disablement of R-rated play.
Encrypted authorization codes that prevent unauthorized publishers from producing playable disks.
Provision of multiple-language audio tracks and multiple-language subtitle tracks on a single disk, with the user specifying the language of choice.
Provision of multiple xe2x80x9cotherxe2x80x9d audio tracks, e.g., each containing some component of orchestral music, with the user choosing the desired mix.
Variable rate encoding of data blocks, and efficient use of bit capacity with track switching and/or mixing, to allow all of the above capabilities on a single carrier.